The invention set forth in this specification pertains to new and improved structural members and to joints between such members.
At the present time increasing interest is being expressed in utilizing so-called stress-skin panels for all sorts of structural applications. Such panels are normally formed so as to include a comparatively weak rigid core such as a core of cellular or foamed polymer material laminated between two side members such as aluminum or similar metal side members. It is not considered that an understanding of the present invention requires a detailed discussion as to why such structural members are considered to be particularly desirable in many different applications.
In utilizing such structural members or panels various problems have been encountered in joining such structural members or panels together in an edge-to-edge relationship. This problem is considered to be much more significant than might normally be realized. Any joint between two such panels or structural members must be desirable from a structural standpoint so as to be capable of transmitting the loads encountered in a particular assembled structure. In addition, however, such a joint preferably should be of such a character that the heat and noise transmission through the joint is the same or substantially the same as such transmission through the panels or structural members. Further, because of labor costs any such joints between two structural members or panels must be of a comparatively simple character, must involve parts which can be manufactured at a comparatively nominal cost, and must be capable of being assembled with minimal difficulty by comparatively unskilled labor.
It is considered that various known prior art joints for joining various tyes of structural members together are not particularly satisfactory for use in connection with stress-skin type structural members or panels as are indicated in the preceding. A wide variety of different types of joints have, of course, been proposed and utilized in connecting members together. Some of such joints are indicated in a number of standard reference works such as the text Engineer's Illustrated Thesaurus by Herkimer, copyright 1952, Chemical Publishing Company, New York.
Such joints as are indicated in this text and in other similar reference works are all considered to be relatively undesirable for use with stress-skin structural members as are indicated in the preceding discussion. It is not considered necessary to discuss the reasons as to why all of such joints are undesirable for use with stress-skin panels or structural members in this specification. However, it is considered that an understanding of this invention will be facilitated by a brief discussion of known scarf and butt joints and splices since such joints and splices are closely related to the present invention.
In such joints and splices it is conventional to form the adjacent interfitting ends of the members being joined so that such ends have closely interfitting "Z" type shapes and to secure such ends together by overlapping or fish plates extending across the abutted ends of the members and secured to both of the members by known fasteners such as bolts. Such joints require that the ends of the members be formed with a reasonably close degree of precision. They require significant hand labor in connection with their assembly. Further, because of the fasteners used with such joints the heat and sound transmission through such joints is normally higher than the heat and sound transmission through the portions of the members adjacent to such joints. As a result of these and various other related considerations it is not considered that known scarf and butt type joints and splices are particularly suitable for use in connecting stress-skin structural panels or members together.